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          <th colspan="3" align="center">Chapter 25. 
 DbstlDbt  </th>
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            <h2 class="title"><a id="DbstlDbt"></a>Chapter 25. 
 DbstlDbt  </h2>
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      <p>You can persist all bytes in a chunk of contiguous memory by constructing an <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 object A(use malloc to allocate the required number of bytes for A.data and copy the bytes to be stored into A.data, set other fields as necessary) and store A into a container, e.g. </p>
      <p>db_vector&lt;DbstlDbt&gt;, this stores the bytes rather than the object A into the underlying database. The <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 class can help you avoid memory leaks, so it is strongly recommended that you use <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 rather than Dbt class.</p>
      <p><a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 derives from Dbt class, and it does an deep copy on copy construction and assignment --by calling malloc to allocate its own memory and then copying the bytes to it; Conversely the destructor will free the memory on destruction if the data pointer is non-NULL. The destructor assumes the memory is allocated via malloc, hence why you are required to call malloc to allocate memory in order to use <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
.</p>
      <p><a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 simply inherits all methods from Dbt with no extra new methods except the constructors/destructor and assignment operator, so it is easy to use.</p>
      <p>In practice you rarely need to use <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 or Dbt because dbstl enables you to store any complex objects or primitive data. Only when you need to store raw bytes, e.g. a bitmap, do you need to use <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
.</p>
      <p>Hence, <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 is the right class to use to store any object into Berkeley DB via dbstl without memory leaks.</p>
      <p>Don't free the memory referenced by <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 objects, it will be freed when the <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 object is destructed.</p>
      <p>Please refer to the two examples using <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 in TestAssoc::test_arbitrary_object_storage and TestAssoc::test_char_star_string_storage member functions, which illustrate how to correctly use <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
 in order to store raw bytes.</p>
      <p>This class handles the task of allocating and de-allocating memory internally. Although it can be used to store data which cannot be handled by the <a class="link" href="DbstlElemTraits.html" title="Chapter 26.  DbstlElemTraits">DbstlElemTraits</a>
 class, in practice, it is usually more convenient to register callbacks in the <a class="link" href="DbstlElemTraits.html" title="Chapter 26.  DbstlElemTraits">DbstlElemTraits</a>
 class for the type you are storing/retrieving using dbstl. </p>
      <h4><a id="idp51587824"></a> Public Members </h4>
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              <th>Member</th>
              <th>Description</th>
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              <td>
<a class="xref" href="DbstlDbt.html#stlDbstlDbtDbstlDbt" title="DbstlDbt">DbstlDbt</a>
</td>
              <td>
   <p>Construct an object with an existing chunk of memory of size1 bytes, refered by data1,. </p>        </td>
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              <td>
<a class="xref" href="stlDbstlDbtdstr_DbstlDbt.html" title="~DbstlDbt">~DbstlDbt</a>
</td>
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   <p>The memory will be free'ed by the destructor. </p>        </td>
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              <td>
<a class="xref" href="stlDbstlDbtoperator_assign.html" title="operator=">operator=</a>
</td>
              <td>
   <p>The memory will be reallocated if neccessary. </p>        </td>
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      <h4><a id="idp51593232"></a>
Group</h4>
      <p>
<a class="xref" href="dbstl_helper_classes.html" title="Chapter 21.  Dbstl Helper Classes">
 Dbstl Helper Classes  </a>
</p>
      <p>
</p>
      <div class="sect1" lang="en" xml:lang="en">
        <div class="titlepage">
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              <h2 class="title" style="clear: both"><a id="stlDbstlDbtDbstlDbt"></a>DbstlDbt</h2>
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        <div class="sect2" lang="en" xml:lang="en">
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                <h3 class="title"><a id="stlDbstlDbtDbstlDbt_details"></a>Function Details</h3>
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          <pre class="programlisting">
DbstlDbt(void *data1,
    u_int32_t size1)
 </pre>
          <p>Construct an object with an existing chunk of memory of size1 bytes, refered by data1,. </p>
          <pre class="programlisting">
DbstlDbt()
 </pre>
          <pre class="programlisting">
DbstlDbt(const DbstlDbt &amp;d)
 </pre>
          <p>This copy constructor does a deep copy. </p>
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                <h3 class="title"><a id="idp51589656"></a>Class</h3>
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          <p>
  <a class="link" href="DbstlDbt.html" title="Chapter 25.  DbstlDbt">DbstlDbt</a>
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